mime: parse media types that contain braces
This CL fixes a bug introduced by CL 666655: isTokenChar would no longer
(but should) report true for '{' and '}'.
Fixes #76236
Change-Id: Ifc0953c30d7cae7bfba9bc4b6bb6951a83c52576
GitHub-Last-Rev:
c91a75c2c8778a9a8343c6bb4fa89eb1f978059f
GitHub-Pull-Request: golang/go#76243
Reviewed-on: https://go-review.googlesource.com/c/go/+/719380
Reviewed-by: Sean Liao <sean@liao.dev>
Reviewed-by: Jorropo <jorropo.pgm@gmail.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>